Semi-active Control Research About The Dynamic Stability Of Rotor/airframe Coupled Basing On Magneto-rheological Damper

The dynamic stability of helicopter rotor/airframe couple is one of the most complicated problems in helicopter design. In order to increase stability, multifarious passive lead-lag damper usually is fitted at the root of blade. But those dampers are hard to meet the demand on damp for stability in different kinds of helicopter working condition. So finding one kind of the lead-lag dampers whose damp is controllable is an effective way to solve this problem. This always is the hot spot in helicopter dynamic design and research. In this thesis the nonlinear hysteretic model is chosen as the mathematical model of magneto-rheological lead-lag dampers. Basing on the vector method of multi-body dynamics, the analysis model of dynamic stability of the rotor/airframe couple using magneto-rheological damper is set up, which can be used in different flights (on ground, in hover and forward flight). In this model, the influence of the dynamic inflow is considered, and the small displacement assumption used to be adopted in modeling is retracted. Comparison is made between the results of Carlman planar model and the one presented in this paper, also is comparison between the simulating results of the latter and the data from one experiment of isolated hovering rotor, which is done on the test stand of rotor/airframe couple in the Helicopter Research Institute of NUAA. The simulating results correlate experimental data very well, and the model used here is verified as well as the analysis method. On this basis, the simulation and analysis of the test stand is fulfilled and the critical rotate speed of ground resonance is gotten Semi-active control method on analysis of the dynamic stability of helicopter rotor/airframe couple using magneto-rheological damper is investigated. Basing on research of fuzzy control, construct two fuzzy controllers and one controller combined with switch control and fuzzy control strategies. Using these controllers, control simulations of the rotor stand in dynamic instability are carried out, and it turned out that these three controllers can increase dynamic stability abundance without exception and the excellence of supplying damp on demand is presented. When compared to the first two controllers, the last one effects poorly and consumes more energy when the sampling frequency is small. Nevertheless, it works better and its energy expend is in lower when the sampling frequency increased to be in certain scope.